Association of Facet Tropism with Lumbar Disk Herniation

Abstract

Introduction Study Design Analytical cross-sectional hospital-based cohort study. Objective (1) To determine whether there is an association between facet tropism and the occurrence of lumbar disk herniation at that level. (2) In patients with facet tropism at the herniated disk level, to determine whether there is an association between facet tropism and the side of disk herniation (sagittal or coronal). Background Facet tropism is defined as asymmetry between left and right facet joint angles and is postulated as a possible etiological cause in occurrence of disk herniation. A correlation in literature is still being debated. Materials and Methods Total 60 patients (18 to 40 years) with single disk herniation (L3-L4, L4-L5, or L5-S1) were selected. Exclusion criteria included multiple/recurrent disk herniation, spondylolisthesis, transitional vertebra, scoliosis, previous surgery/trauma/infection, and significant facetal arthropathy. Facet angles were measured using 3 Tesla MRI by two surgeons and mean taken to minimize bias. Facet tropism was defined as difference of 10 degrees in facet joint angles between right and left sides. Normal adjacent disk was used as control. We also examined if disk herniated towards the side of more coronally oriented facet. Results Overall we found a statistically significant association of facet tropism with lumbar disk herniation ( p = 0.0009). However, analyzing each level separately, an association of facet tropism with lumbar disk herniation was found to be statistically significant at the L5S1 level ( p = 0.0094) but not at L4L5 level ( p = 0.145). Of 19 cases having tropism at the herniated disk level, the disk had herniated towards the sagittally oriented facet in 13 ( p = 0.11). Conclusion Statistically significant association exists between facet tropism and lumbar disk herniation at L5-S1. Same does not hold true at L4-5. There is no statistically significant association between facet tropism and the side of the disk herniation (sagittal or coronal) but the numbers were small. I confirm having declared any potential conflict of interest for all authors listed on this abstract Yes Disclosure of Interest None declared